\\[-1.8ex] Soil Heterogeneity & $-$0.087$^{**}$ & $-$0.027 & $-$0.027 & $-$0.032$^{*}$ & $-$0.020 & $-$0.029$^{**}$ \\ 
  & (0.044) & (0.023) & (0.021) & (0.019) & (0.015) & (0.015) \\ 
\\[-1.8ex] 
Oster $\delta$ for $\beta=0$ &  & 0.79 & 0.87 & 1.20 & 0.67 & 1.05 \\ 
Observations & 23,532 & 23,532 & 23,532 & 23,532 & 23,532 & 23,470 \\ 
R$^{2}$ & 0.007 & 0.625 & 0.662 & 0.677 & 0.685 & 0.691 \\ 
